We arrived pretty late at BKK, but the pickup worked perfectly fine (however, you need a possibility to contact them to pick you up when you arrive at the described meeting point).
Needed a transfer to BKK the next morning. The charge therefore is 150 Baht, and your preferred shuttle time may already been taken by others guests (they have 30 or 40 minutes slots per guests).
In total, good place for a one night stay around BKK airport!